1. Field of the Invention
The present invention relates to an image processing technology for compressing the dynamic range of input image data.
2. Description of the Related Art
Japanese Unexamined Patent Publication No. 2003-8898 discloses a technology directed to realizing a smoothing process without using a large-sized filter, with substantially the same effect and operation as in the case of using a large-sized filter. In this technology, an illumination component is extracted from the input image data by: generating multiple smooth image data whose degree of smoothness is different from each other from input image data; calculating an edge intensity based on the multiple smooth image data; and combining the multiple smooth image data based on the calculated edge intensity.
The above publication, however, has no disclosure on an arrangement as to how color image data obtained by an image sensor having different spectral sensitivities with respect to each of the pixels is processed. Accordingly, in the technology disclosed in the publication, it may be impossible to precisely extract an illumination component from color image data.